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[2603:8081:140c:1a00:6b28:6b74:44a5:2cfa]) by smtp.gmail.com with ESMTPSA id x21-20020a05687031d500b001b02a3426ddsm1979496oac.14.2023.07.19.07.34.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 19 Jul 2023 07:34:44 -0700 (PDT) Message-ID: <5a036610-a51e-98ec-5319-1d7ce01b15a9@gmail.com> Date: Wed, 19 Jul 2023 09:34:43 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH for-next 2/2] RDMA/rxe: Enable rcu locking of indexed objects To: Zhu Yanjun Cc: jgg@nvidia.com, leon@kernel.org, linux-rdma@vger.kernel.org, jhack@hpe.com References: <20230718175943.16734-1-rpearsonhpe@gmail.com> <20230718175943.16734-3-rpearsonhpe@gmail.com> Content-Language: en-US From: Bob Pearson In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On 7/19/23 00:38, Zhu Yanjun wrote: > On Wed, Jul 19, 2023 at 2:00 AM Bob Pearson wrote: >> >> Make rcu_read locking of critical sections with the indexed >> verbs objects be protected from early freeing of those objects. >> The AH, QP, MR and MW objects are looked up from their indices >> contained in received packets or WQEs during I/O processing. >> Make these objects be freed using kfree_rcu to avoid races. >> >> Signed-off-by: Bob Pearson >> --- >> drivers/infiniband/sw/rxe/rxe_pool.h | 1 + >> drivers/infiniband/sw/rxe/rxe_verbs.c | 6 +++++- >> 2 files changed, 6 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/infiniband/sw/rxe/rxe_pool.h b/drivers/infiniband/sw/rxe/rxe_pool.h >> index b42e26427a70..ef2f6f88e254 100644 >> --- a/drivers/infiniband/sw/rxe/rxe_pool.h >> +++ b/drivers/infiniband/sw/rxe/rxe_pool.h >> @@ -25,6 +25,7 @@ struct rxe_pool_elem { >> struct kref ref_cnt; >> struct list_head list; >> struct completion complete; >> + struct rcu_head rcu; >> u32 index; >> }; >> >> diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c >> index 903f0b71447e..b899924b81eb 100644 >> --- a/drivers/infiniband/sw/rxe/rxe_verbs.c >> +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c >> @@ -1395,7 +1395,7 @@ static int rxe_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata) >> if (cleanup_err) >> rxe_err_mr(mr, "cleanup failed, err = %d", cleanup_err); >> >> - kfree_rcu_mightsleep(mr); >> + kfree_rcu(mr, elem.rcu); >> return 0; >> >> err_out: >> @@ -1494,6 +1494,10 @@ static const struct ib_device_ops rxe_dev_ops = { >> INIT_RDMA_OBJ_SIZE(ib_srq, rxe_srq, ibsrq), >> INIT_RDMA_OBJ_SIZE(ib_ucontext, rxe_ucontext, ibuc), >> INIT_RDMA_OBJ_SIZE(ib_mw, rxe_mw, ibmw), >> + >> + .rcu_offset_ah = offsetof(struct rxe_ah, elem.rcu), >> + .rcu_offset_qp = offsetof(struct rxe_qp, elem.rcu), >> + .rcu_offset_mw = offsetof(struct rxe_mw, elem.rcu), > > In your commits, you mentioned that ah, qp, mw and mr will be > protected. But here, only ah, qp and mw are set. > Not sure if mr is also protected and set in other place. > Except that, I am fine with it. > > Acked-by: Zhu Yanjun > > Zhu Yanjun > >> }; >> >> int rxe_register_device(struct rxe_dev *rxe, const char *ibdev_name) >> -- >> 2.39.2 >> All of the verbs objects except MR are allocated and freed by rdma-core. MR is allocated and freed by the drivers. So for MR the kfree_rcu call is made in rxe_dereg_mr(). I changed it from kfree_rcu_mightsleep to the kfree_rcu variant to match the three others. Bob